For compact disc (CD) and DVD (Digital Versatile Disc or Digital Video Disc) and the like, various copy-prevention arts for preventing illegal copy are proposed and practically used in order to protect copyrights. For example, SCMS (Serial Copy Management System) permits a first-generation copy from a CD to an MD (Mini Disc: trade mark) but inhibits a second-generation copy from an MD to other medium. Moreover, a copy-generation restriction system is also known which restricts what-th generation copy can be generated.
Moreover, music contents have been recently circulated in accordance with quick advancement of networks including Internet. Under the above situation, EMD (Electronic Music Distribution) using networks such as Internet and satellite broadcasting has been started and a copyright management method for EMD is proposed. In the case of EMD, a user can obtain music contents through charging. The above-described arts such as SCMS and copy generation restriction are going to be used for the EMD in order to prevent illegal copy.
As described above, the conventional copyright protection method has restricted copy by using a copy prevention art to protect the right of a writer. Therefore, the method has been an obstacle for circulating music contents widely in a short time. For example, a due system is one of conventional copyright protection systems. This system is executed by a DAT (Digital Audio Taperecorder) or MD, in which a user of a digital recorder pays a compensation added to a product price. In these days in which networks are advanced, hardware (player or medium) does not frequently correspond to contents distributed through a network one to one so that the contents are received by a personal computer and reproduced and therefore, it cannot be said that the above due system is suitable as a copyright protection system.
Moreover, a plurality of melodies are recorded in a medium such as a CD, a user may enjoy only one specific melody or only several melodies among the recorded melodies or may not want to buy the whole medium, that is, the DC. Furthermore, advertisement and circulation of music contents may be prevented due to a copying-prevention technique. It is possible to advertise and circulate the music contents for a short time by distributing the music contents free of charge and reduce the cost for advertisement and circulation of them.
When considering the above point, it is preferable to use a system in which contents are circulated and widely distributed free of charge and charged when reproducing the contents so that the contents are easily and quickly circulated and a writer can obtain a legal compensation. To realize the above system, it is necessary that contents recorded in a medium are encrypted. Moreover, it is considered to construct a system that is charged when the encrypted contents are reproduced. However, there is a problem that a recording medium storing encrypted contents such as a disk cannot be reproduced by an existing disk reproducing apparatus such as a CD reproducing apparatus.
Moreover, it is preferable that copy (redistribution) can be freely performed in addition to the fact that contents can be circulated and distributed free of charge. In this case, encrypted contents are copied. It is preferable that the copying time required is short.
Therefore, it is an object of the present invention to provide a recording medium storing contents that can be charged when decoded by being encoded while securing the compatibility with an existing data-recording medium.
Moreover, it is another object of the present invention to provide a recording medium for recording and reproducing data in and from the former recording medium and controlling copy, data recording method and apparatus, data reproducing method and apparatus, and a copy control method.